Thank you very much for all those detail instructions. I developed a major application (ERP system) in HMG using mySQL instead of .dbf files. This application builds fine in 32 bit.
When following your instructions to build in 64 bit I encountered the following two problems

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Hello friend joerg
The error that can not deverse, you followed the instructions
you send?
the page that put Rathinagiri -> HMG 3.4.3

discharge:
You can download esta latest version from "here" (64 MB) <- Click where it says "here"

discharge:
You can download latest version esta from "here" (64 MB) <- Click where it says "here"
and then also in "here" Harbour64 libraries and MingW64
For 64 Bit developers, You have to download and install Harbour64 and MingW64 from "here" (15 MB) and "here" (71 MB) respecitvely.

Create a directory like I have -> c:\hmg.3.4.3_64 then install HMG 3.4.3 64-bit, put MinGW HARBOUR-64 and I-64 and I put
then put the LIB-64 to send to the Web and passes _BuildAllLib64.bat runs

Great help by Mustafa and melliott42. Due to your help I got my first 64bit program running.
I couldn't rebuild lib for 64 using _BuildAllLib64 building process stopped before all libraries could be built.
Mutafa's lib-64.zip file came very helpful.